Hello! Are in progress of a site listings motor vehicles and auto parts. I have a question: When can I enroll in G. Adsense site to be accepted for sure? I have to many ads on the site or can I register it without content ...

You're question is not so clear to me... Google Adsense will have to review you're site first, depending on your site, they may accept or reject your application.. if you have a very new site with barely any content, there is a good chance that they might reject it...

There's no point in applying for an AdSense account until the site is attracting a significant amount of traffic. You'll need to be getting a least several hundred visitors per day over a long period before you should think about AdSense - or any similar system. And, of course, you won't get any traffic until you have some worthwhile content. So, for now, focus on developing the site, and don't worry about AdSense until the site is established.